Like BW we have those ruins in BW2, but when we finish the main story-line, we can find in undella town a plasma sage and he will give us ghetis notebook which translate us the text in the ruins from ancient language to japanese and when we go to the 4th floor we can notice some black points in the text instead of the 3, 4, 5 and 6(the king) symbols in BW1, if someone understand japanese, please translte us to english

The Abyssal Ruins in Black/White were in fact, already decoded long ago.
They were just substitute characters for japanese characters, so anyone playing the game in japanese could have decoded it, and have.

Said decoded japanese has already been translated to english.
http://bulbapedia.bulbagarden.net/wiki/Abyssal_Ruins

It's funny because the cryptic text was left unchanged in international releases, meaning for English players or players of other languages, solving the runes would have been a near impossibility.

This doesn't make sense in Japanese, it's just nonsense. It's not even "ancient" Japanese; I can at least recognize old-style Japanese text, but I don't recognize any of this. The text above wouldn't make sense even to a native Japanese speaker.

I haven't played the game, but my guess is that you need to use that Ghetis Notebook (or whatever you called it) to "decrypt" it into real Japanese.

Paste the real (decrypted) Japanese message on here, and maybe I'll be able to help. I'm not about to go look for the ROM, download it and play through the game just to get to the 4th floor of the Abyssal Ruins to translate one piece of "fake" Japanese text.

The Abyssal Ruins of Black 2 and White 2 have already been translated using the rules provided by Vio of Sazanami Town (Zinzolin of Undella Town). (as per http://www57.atwiki....2/pages/68.html ) The readings hew closely to those of Black and White with the symbols being replaced by the character-stand-in black circles, but from how that wiki page looks, it does not appear that the black circles are ever replaced by characters.

The Abyssal Ruins of Black 2 and White 2 have already been translated using the rules provided by Vio of Sazanami Town (Zinzolin of Undella Town). (as per http://www57.atwiki....2/pages/68.html ) The readings hew closely to those of Black and White with the symbols being replaced by the character-stand-in black circles, but from how that wiki page looks, it does not appear that the black circles are ever replaced by characters.

Decoded:
You need to:
- read each line backward (from right to left),
- shift every character up three in the Japanese "alphabet"
- (ex: い→を、あ→わ, but you'd have to know the order of the "alphabet" in order to know how to do that)
4F
1.王はたった一人で●●●●を跳ね除けた
2.●●●●は直ぐに王の仲間になった
3.王は●●●●を生き物と呼んだ
4.王は私たちの希望であり未来である
5.ここに偉大なる王●●●●●を称える

Translated:
4F
1.The king single-handedly got rid of the ●●●●
2.The ●●●● soon became friends with the king
3.The king called ●●●● a living being (living thing, animal, etc.)
4.The king is our hope, our future
5. In this place we extol the great King ●●●●● (the blank is probably the king's name)